03-29341. Airworthiness Directives; Boeing Model 707 and 720 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Boeing Model 707 and 720 series airplanes. This proposed AD would require inspection of the bolt forward of the wing front spar upper chord on the overwing support fittings of the inboard and outboard nacelle struts to verify that BACB30US type bolts are installed. If any other type of bolt is found, this proposed AD would require replacement with a new BACB30US type bolt. This action is necessary to prevent separation of the engine from the airplane due to stress corrosion cracking and consequent fracturing of the bolts. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by January 9, 2004.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-334-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2002-NM-334-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 or 2000 or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Candice Gerretsen, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2002-NM-334-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-334-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports indicating that several fractured H-11 steel bolts have been found on the underwing strut attachment fitting on Boeing Model 767 series airplanes. The cause of the H-11 steel bolt fracture was due to stress corrosion. This condition, if not corrected, could result in separation of the engine from the airplane due to stress corrosion cracking and consequent fracturing of the bolts.

The H-11 steel bolts forward of the wing front spar upper chord on the overwing support fittings of the inboard and outboard nacelle struts on certain Boeing Model 707 and 720 series airplanes are identical to those on the affected Boeing Model 767 series airplanes. Therefore, all these airplanes may be subject to the same unsafe condition.

Other Relevant Rulemaking

The FAA has previously issued AD 2000-10-51, amendment 39-11770 (65 FR 37011, June 13, 2000), applicable to certain Boeing Model 767 series airplanes. That AD requires an inspection of the 767 underwing strut attachment fitting to determine whether H-11 steel tension bolts are installed in the side load underwing fittings on both struts. This proposed AD would not affect the current requirements of that AD.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing 707/720 Service Bulletin A3502, dated February 21, 2002, which describes procedures for performing a general visual inspection of the bolt forward of the wing front spar upper chord on the overwing support fittings of the inboard and outboard nacelle struts to verify that BACB30US type bolts are installed, and performing corrective actions if any other type bolt is found. The corrective actions consist of performing a high frequency eddy current inspection of the hole bore for corrosion and cracks; measuring the hole to verify the diameter is within the specified dimensions; contacting the manufacturer for corrective action if any crack or corrosion is found or if hole diameter is not within the specified dimensions; and replacing non-BACB30US type bolts with new BACB30US type bolts. The new BACB30US bolts are made from nickel alloy 718 material and are not subject to stress corrosion. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the service bulletin described previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

Operators should note that, although the service bulletin specifies that reviewing records is another way to verify if a BACB30US type bolt is installed, this proposed AD would require performing a general visual inspection as the only way to verify if a BACB30US type bolt is installed. The FAA has determined that even if a BACB30US type bolt had been installed as shown on the records, the BACB30US type bolt could have been replaced at a later time with a bolt other than a BACB30US type bolt. Therefore, a general visual inspection is the only way to verify if a BACB30US type bolt is installed.

Operators should note that, although the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this proposed AD would require the repair of those conditions to be accomplished per a method approved by the FAA, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the FAA to make such findings.

Cost Impact

There are approximately 230 airplanes of the affected design in the worldwide fleet. The FAA estimates that 42 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 1 work hour per airplane to accomplish the proposed inspection and that the average labor rate is $65 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $2,730, or $65 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

Boeing: Docket 2002-NM-334-AD.

Applicability: All Model 707 and 720 series airplanes, as listed in Boeing 707/720 Service Bulletin A3502, dated February 21, 2002; certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent separation of the engine from the airplane due to stress corrosion cracking and consequent fracturing of the bolts, accomplish the following:

Service Bulletin References

(a) The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing 707/720 Service Bulletin A3502, dated February 21, 2002.

Inspection and Corrective Action

(b) Except as provided by paragraph (c) of this AD, within 12 months from the effective date of this AD, perform a general visual inspection of the bolts forward of the wing front spar upper chord on the overwing support fittings of the inboard and outboard nacelle struts to verify that BACB30US type bolts are installed, per Figure 1 of the service bulletin.

Note 1:

For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to enhance visual access to all exposed surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

(c) The service bulletin specifies that reviewing records is another way to verify if a BACB30US type bolt is installed. However, this AD does not allow that alternative. The general visual inspection required by paragraph (b) of this AD must be accomplished to verify if BACB30US type bolts are installed.

(d) If any bolt other than the BACB30US type bolts specified in Figure 1 of the service bulletin is found during the inspection required by paragraph (b) of this AD or if any bolt cannot be identified: Prior to further flight, do the actions specified in paragraphs (d)(1) and (d)(2) of this AD, per Figure 2 of the service bulletin.

(1) Perform a high frequency eddy current (HFEC) inspection of the hole bore for cracks and corrosion and measure the hole to verify the diameter is within the specified dimensions. If any corrosion or cracking is found or if the measured hole diameter is not within the specified dimensions, and the service bulletin specifies to contact Boeing for appropriate action: Prior to further flight, repair per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved, the approval must specifically reference this AD.

(2) Replace the bolt with a new BACB30US type bolt per Figure 2 of the service bulletin.

Parts Installation

(e) As of the effective date of this AD, no person shall install any bolt other than a BACB30US type bolt in the locations specified in this AD, on any airplane.

Alternative Methods of Compliance

(f) In accordance with 14 CFR 39.19, the Manager, Seattle Aircraft Certification Office, FAA, is authorized to approve alternative methods of compliance for this AD.

Issued in Renton, Washington, on November 17, 2003.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.